It is often noticed during searches on InPASS, Espacenet or PATENTSCOPE that results are tagged with mysterious strings like A61K 8/00 or H04W 4/70. Applicants frequently ask whether these codes must be filled in at filing, how they affect examination, and whether CPC is different from IPC. Understanding these labels early improves searching, drafting, and responses to examination.
IPC in plain terms, and why it exists
The International Patent Classification or IPC is a WIPO administered, treaty-based system for classifying patent documents across the world. It was established under the Strasbourg Agreement, and a new version becomes effective on 1 January each year. IPC symbols are language-independent and hierarchical, which makes them ideal for prior art retrieval across jurisdictions.
IPC divides technology into eight high-level Sections A to H. Each section breaks down into Classes, Subclasses, Groups, and Subgroups. A full IPC symbol such as A61K 8/00 conveys the section, class, subclass and group for a specific technical area. The WIPO Guide to the IPC explains this structure and how to read symbols when classifying or searching.
Two practical points flow from this. First, IPC is mainly an information retrieval tool, used to organise prior art and make searching efficient. Second, assigning an IPC symbol does not expand or restrict the legal scope of your claims. It is an indexing label, not a rights conferrer.
CPC, the more granular cousin
The Cooperative Patent Classification or CPC is a joint EPO-USPTO system built as an extension of IPC. CPC also uses sections A to H, and adds Section Y for cross-sectional, emerging technologies. It is intentionally more detailed, with roughly 250,000 entries, which is why CPC often feels more precise for deep searches in cutting-edge fields.
CPC is maintained by the EPO and USPTO, and is used to classify European and US publications, among others. For searchers in India, CPC is helpful because a large volume of global prior art, especially in fast-moving domains, is tagged with CPC even when an Indian document is not.
How India uses classification in practice
In India, you will interact with classification in three routine places.
At filing and on forms
Form 1 captures priority details for convention filings and explicitly asks for the IPC as classified in the convention country. For PCT national phase entries, the international publication already carries IPC symbols, which flow into the Indian record.In searches
The public search portal InPASS allows filtering by International Patent Classification (IPC), which helps narrow Indian publications by technical area. This aligns with global practice where examiners assign at least one IPC symbol to each patent document.During examination
Examiners rely on IPC and CPC to retrieve relevant prior art quickly. The classification label supports the search process, but the allowability of claims is still tested against statutory patentability criteria and the cited documents, not against the label itself.
IPC vs CPC for Indian applicants, at a glance
Ownership and scope
CPC, co-managed by EPO and USPTO, is an expanded, finer-grained scheme.
Granularity
IPC is compact and broadly descriptive.
CPC provides more sub-groups and the special Y section for cross-cutting tech.
Where you will see them
Indian filings and journals display IPC. In global databases, European and US documents show CPC alongside IPC.
What to use for searching
Start with IPC to frame the area, then employ CPC for precision, especially when your technology overlaps with US or European prior art.
Reading the code: a quick primer
Take H04W 4/70 as an example.
H, Section Electricity
H04, Class Electric communication technique
H04W, Subclass Wireless communication networks
4/70, Group and subgroup that define a specific concept within that subclass
The IPC Guide sets out this hierarchy and the conventions for symbols, spacing and slashes. If you are new to this, reviewing the Guide once pays long-term dividends for drafting searches and for claim strategy.
Where to find the right codes quickly
Use a simple three-step routine before filing or searching:
Scan the WIPO IPC Publication
Type a few keywords and review the suggested sections and groups. Use the “definition” pages to confirm you are in scope and to check “references” that redirect to more precise areas.Jump to CPC for depth
Open the EPO CPC browser and locate the corresponding CPC subgroup. Check the notes and indexing schemes under the subgroup, which often expose highly specific terms seen in examination.Test the codes in the databases
In India, run IPC filters in InPASS and scan the results list to sanity-check relevance.
In PATENTSCOPE and Espacenet, search by IPC and CPC together to catch both global and region-specific documents.
Do these labels affect my patentability?
No, not directly. Classification organises documents and speeds up search. Patentability turns on the claims, the disclosure, and the cited prior art. A wrong or imprecise IPC will not by itself defeat an otherwise allowable claim, though it may lead to less targeted prior art being retrieved initially. The WIPO materials repeatedly position IPC as a retrieval and arrangement tool, not a legal boundary.
What should I put in my Indian filing?
A simple checklist helps.
For a convention filing, fill in the IPC used in the convention country on Form 1.
For a PCT national phase, you need not invent a label. The WO publication carries IPC and the Indian record will reflect it.
For an ordinary Indian filing, the Office will classify. It is still good practice to propose the most accurate IPC in your cover or specification header to aid indexing and search. Examiners may revise or refine classification during processing.
How to use IPC and CPC in drafting and prosecution
Prior art landscaping
Build a classification map for your core features. Note the neighbouring groups and any “references out” that might contain close alternatives. This prevents blind spots in novelty and inventive step analysis.Claim layering
If two adjacent groups reflect alternative structures, consider dependent claims that capture both, so search and examination do not miss a path only because one label was chosen at filing. This is especially useful where CPC sub-groups are very fine.Responding to the FER
When exam citations cluster in certain IPC or CPC groups, review the group definitions and notes. If the cited art belongs to a neighbouring concept, use the definition text to argue that your claimed features sit outside that conceptual boundary.Freedom-to-operate scans
Run CPC-heavy filters when the market is US or Europe facing, since many cutting-edge portfolios are indexed with CPC first, then IPC.
Quick answers to common doubts
Is CPC mandatory in India?
No. India’s filings and searches are anchored on IPC. CPC is a search asset, not a filing requirement at the Indian Patent Office.Will the Controller refuse if my IPC is wrong?
Not for that reason alone. Classification serves retrieval. If a correction is needed, the Office can reclassify during processing. Your claim text and the statutory tests remain decisive.Does IPC change over time?
Yes. A new version of IPC enters into force on 1 January each year. This is why modern databases display the current symbol and may also show historic versions for older documents.Why does a US or EP document show more granular labels than my Indian search?
Those jurisdictions use CPC extensively, which contains far more entries and an extra Y section. Pairing CPC with IPC in your searches usually solves this asymmetry.Practical workflow you can reuse
Start with two or three keywords that capture your inventive feature.
Open the WIPO IPC browser and shortlist 2 to 4 IPC groups and subgroups that truly fit.
Translate those to CPC using the EPO CPC site, noting any narrower CPC subgroups and indexing schemes.
Run searches on InPASS using IPC for Indian literature, then repeat on PATENTSCOPE and Espacenet with both IPC and CPC.
Capture the recurrent codes in your internal notes, and keep this list updated when new prior art is spotted in examination.
Getting comfortable with IPC and CPC pays off throughout the life of a patent. Better codes mean sharper searches, stronger drafting, and fewer surprises during prosecution.
